JP6174249B2 - User terminal, radio base station, and radio communication method - Google Patents

Description

  The present invention relates to a user terminal, a radio base station, and a radio communication method in a next generation mobile communication system.

  In the UMTS (Universal Mobile Telecommunications System) network, Long Term Evolution (LTE) has been specified for the purpose of higher data rate and low delay (Non-patent Document 1). In addition, a successor system of LTE (for example, LTE Advanced (LTE-A), FRA (Future Radio Access), 4G, etc.) is also being studied for the purpose of further widening and speeding up from LTE.

  In LTE and LTE-A, discontinuous reception (DRX: Discontinuous reception) in which a user terminal switches off a receiving circuit at a predetermined period is employed (Non-Patent Document 2). By applying DRX, it is possible to reduce the power consumption of the user terminal.

3GPP TS 36.300 “Evolved Universal Terrestrial Radio Access (E-UTRA) and Evolved Universal Terrestrial Radio Access Network (E-UTRAN); Overall description; Stage 2” 3GPP TS 36.321 “Evolved Universal Terrestrial Radio Access (E-UTRA); Medium Access Control (MAC) protocol specification”

  In the existing discontinuous reception (DRX) operation, the user terminal receives a timer (for example, drx-InactivityTimer) that is activated by reception of a downlink control signal (PDCCH) or a MAC control element that instructs a transition to a DRX state (for example, DRX) The transition to the DRX state is controlled based on MAC CE). On the other hand, even if the user terminal that is in the non-DRX state by performing data transmission / reception does not perform data transmission / reception until drx-InactivityTimer expires or until there is a notification of DRX MAC CE, etc. It will operate in the Active state.

  In the LTE-A system and later, it is assumed that the user terminal performs wireless communication using a plurality of basic frequency blocks (component carriers), and further reduction in power consumption is required.

  The present invention has been made in view of such a point, and an object of the present invention is to provide a user terminal, a radio base station, and a radio communication method capable of further reducing power consumption in the user terminal as compared with existing DRX control. One of them.

One of the user terminals of the present invention includes a receiving unit that receives a DL signal including at least a UL grant, and a DRX control unit that controls intermittent reception operation, and the DRX control unit includes a DL including the UL grant. when receiving the signal, and controls the intermittent receiving operation based on the information that is part of to the DL signal.

  According to the present invention, it is possible to further reduce power consumption in a user terminal as compared with existing DRX control.

It is explanatory drawing of discontinuous reception (DRX) control. It is another explanatory view of discontinuous reception (DRX) control. It is explanatory drawing of an example of the intermittent reception (DRX) control using DRX MAC CE. It is explanatory drawing of an example of the intermittent reception (DRX) control in this Embodiment. It is explanatory drawing of another example of the intermittent reception (DRX) control in this Embodiment. It is explanatory drawing of another example of the intermittent reception (DRX) control in this Embodiment. It is a figure which shows an example of the operation | movement flow of discontinuous reception (DRX) control in this Embodiment. It is a figure which shows an example of the MAC CE format utilized for discontinuous reception (DRX) control in this Embodiment. It is the schematic which shows an example of the radio | wireless communications system which concerns on this Embodiment. It is a whole block diagram of the wireless base station which concerns on this Embodiment. It is a functional block diagram of the radio base station which concerns on this Embodiment. It is a whole block diagram of the user terminal which concerns on this Embodiment. It is a functional block diagram of the user terminal which concerns on this Embodiment.

  As described above, in the LTE / LTE-A system, discontinuous reception (DRX) control is adopted for the purpose of battery saving of the user terminal. In DRX control, a user terminal in RRC_CONNECTED (a state in which an RRC connection is established with a radio base station) is managed in two states of “Active state” and “Inactive state”.

  The user terminal in the active state monitors downlink control channels (including PDCCH: Physical Downlink Control Channel, EPDCCH: Enhanced Physical Downlink Control Channel; hereinafter referred to as PDCCH). Also, feedback information (CQI: Channel Quality Indicator / PMI: Precoding Matrix Indicator / RI: Rank Indicator / PTI: Channel State Information (CSI)) and uplink reference signal (SRS: Sounding Reference Signal) is reported.

  On the other hand, the user terminal in the inactive state does not monitor the downlink control channel and does not report feedback information. Thereby, it becomes possible to suppress the battery consumption of the user terminal.

  FIG. 1 shows an example of intermittent reception (DRX) control. 1A shows a case where the user terminal transitions (transitions) to the discontinuous reception (DRX) state due to expiration of drx-inactivityTimer, and FIG. 1B illustrates a MAC control element (DRX command MAC control for instructing transition to the DRX state) Element) shows a case where the user terminal transitions to intermittent reception.

  The DRX cycle (DRX cycle) specifies a cycle in which an ON period and a sleep period following the ON period are combined. In the ON period, the user terminal is in an active state and receives a downlink signal such as PDCCH. On the other hand, in the sleep period, the user terminal stops receiving downlink signals such as PDCCH.

  In FIG. 1, when the user terminal succeeds in decoding the PDCCH for the user terminal in the on period, the user terminal activates drx-InactivityTimer. Here, drx-InactivityTimer is a timer indicating a predetermined period after successfully decoding PDCCH.

  As shown in FIG. 1A, the user terminal continues to be active until drx-InactivityTimer expires, and starts the above DRX cycle when drx-InactivityTimer of the last received PDCCH expires (intermittently). (Transition to receive state). Also, when the user terminal succeeds in decoding the PDCCH for the user terminal before the expiration of the drx-InactivityTimer, the user terminal restarts the drx-InactivityTimer.

  Also, as shown in FIG. 1B, the user terminal sets a DRX cycle when receiving a predetermined MAC control element (DRX MAC CE: DRX command MAC Control Element) even before drx-InactivityTimer expires. Start. That is, the user terminal that has received DRX MAC CE forcibly stops drx-InactivityTimer and transitions to an intermittent reception state. In this way, the radio base station can transition the user terminal to the intermittent reception state by using DRX MAC CE.

  However, since the existing DRX MAC CE (DRX command MAC Control Element) is transmitted through the downlink shared channel (PDSCH), the user terminal can be forced to transit to the DRX state only during DL allocation control for the user terminal. . For this reason, the user terminal cannot be forced to transit to the intermittent reception state at the time of UL allocation control for the user terminal (at the time of UL grant transmission) (see FIG. 2). As a result, even if there is no transmission / reception data thereafter, the user terminal to which the UL grant is assigned is in the Active state from the UL grant assignment time to a predetermined period (for example, when drx-InactivityTimer expires).

  As described above, the present inventors have studied DRX control after UL grant allocation, paying attention to the fact that the existing DRX control does not provide sufficient battery saving at the user terminal after UL grant allocation control.

  For example, a method is conceivable in which an existing DRX MAC CE is transmitted immediately after the UL grant is assigned, and the user terminal is forced to transit to the intermittent reception state (see FIG. 3). However, in such a case, the DL signal must be transmitted only for the user terminal to transition to the intermittent reception state, and there is a possibility that the utilization efficiency of the radio resource is lowered.

  Therefore, the present inventors have conceived a control method for transitioning a user terminal to an intermittent reception state when instructing UL allocation using a UL grant (at the time of UL grant transmission). Specifically, when instructing the UL grant to the user terminal, information (DRX transition instruction information) instructing whether or not to transit to the intermittent reception state is also notified (see FIG. 4).

  The user terminal that has received the UL grant controls the intermittent reception operation according to the content of the DRX transition instruction information. The DRX transition instruction information may be information that instructs the user terminal that has received the UL grant when to transition to the intermittent reception state, and instructs that the drx-InactivityTimer is not started or restarted. It is good also as information to do.

  Thus, by notifying the user terminal together with the DR grant transition instruction information together with the UL grant, the user terminal can immediately transition to the intermittent reception state even after receiving the UL grant. Thereby, compared with the existing DRX control, power consumption in the user terminal can be further reduced. In addition, since it is not necessary to transmit a DL signal only for an intermittent reception instruction to a user terminal, it is possible to suppress a decrease in utilization efficiency of radio resources.

  Moreover, in this Embodiment, the UL grant with respect to a user terminal and the transition instruction | indication to an intermittent reception state can be performed using downlink control information (DCI) or a MAC control element (MAC CE). Below, the case where each control information is utilized is demonstrated.

(First aspect)
In the first aspect, a case will be described in which downlink control information (DCI) is used to give a user terminal a transition instruction to UL grant and intermittent reception at the same timing.

  In the first aspect, the radio base station can instruct the DRX transition to the user terminal using downlink control information (DCI) including the UL grant. For example, the radio base station sets a bit field for DRX transition instruction information in downlink control information (DCI), and allocates the DCI to the downlink control channel (PDCCH). As the downlink control information, DCI formats 0, 4 and the like can be used.

  The user terminal receives the downlink control channel including the UL grant and detects a bit (DRX transition instruction information) indicating whether or not to perform the DRX transition. When transition to intermittent reception is instructed in the received downlink control information, the user terminal transitions to the intermittent reception state. For example, the user terminal does not start drx-InactivityTimer, and transitions to the intermittent reception state after the on-period has elapsed (see FIG. 4).

  In addition, when the transition to the intermittent reception state is instructed together with the UL grant instruction, the user terminal does not immediately transition to the intermittent reception state, but after a predetermined period of time after detecting the bit related to the DRX transition instruction information You may control to transfer to an intermittent reception state (refer FIG. 5). The predetermined period may be set shorter than the period of drx-InactivityTimer. Thereby, when there is data transmission / reception within the predetermined period from the time of UL grant allocation, communication can be performed appropriately. Moreover, it becomes possible to flexibly control the timing at which the user terminal transitions to the intermittent reception state.

  Further, in the present embodiment, the user terminal separately receives an instruction to start or restart the drx-Inactivity Timer before transitioning to intermittent reception after receiving the DRX transition instruction (for example, within a predetermined period in FIG. 5). In this case, the transition operation to the intermittent reception by the DRX transition instruction may be stopped (see FIG. 6). Accordingly, even when continuous data is generated immediately after the eNB decides to perform DRX transition of the user terminal, communication can be performed without causing the user terminal to perform DRX transition unnecessarily.

  At this time, the user terminal can be configured to stop the transition operation to intermittent reception only when the PDCCH instructing activation or reactivation of drx-InactivityTimer is received a predetermined number of times. Thereby, the probability of returning to non-DRX (non-DRX) due to a false detection of PDCCH can be reduced.

  In addition, even when the user terminal is instructed to transition to intermittent reception, the user terminal can intermittently receive the acknowledgment signal (ACK) for the UL data signal (PUSCH signal) transmitted based on the UL grant. The transition to reception may be stopped. That is, when the user terminal cannot receive an ACK for the PUSCH, the user terminal may operate so as not to make a transition to DRX in anticipation of a retransmission PDCCH from the radio base station. In this manner, data transmission / reception can be appropriately performed by controlling the transition operation to intermittent reception in consideration of the positive delivery confirmation signal for the PUSCH signal.

  Note that whether or not to apply the DRX transition cancellation operation in the user terminal may be controlled using an RRC signal or a MAC signal from the radio base station. Thereby, it becomes possible to perform DRX control in a user terminal more flexibly according to a communication condition.

  In the above description, the user terminal instructed to perform DRX transition has performed an operation of transitioning to discontinuous reception (DRX). However, the present invention is not limited to this, and the operation of not starting or restarting drx-InactivityTimer. You may go. That is, the radio base station may instruct the user terminal not to start or restart drx-InactivityTimer together with the UL grant instruction by using the downlink control information (DCI).

  Next, an example of an operation method in the case of performing UL grant and DRX instruction using downlink control information will be described with reference to FIG.

  First, the radio base station transmits downlink control information (DCI) including a UL grant to the user terminal using a downlink control channel (PDCCH / EPDCCH). On the other hand, the user terminal receives the downlink control information (UL grant) (ST101). The user terminal performs transmission control of UL data (PUSCH signal) based on the received UL grant.

  Further, the user terminal determines whether the received downlink control information (DCI) is instructed to transition to intermittent reception (DRX) (ST102). For example, the user terminal detects DRX transition instruction information included in the downlink control information, and determines whether or not there is a transition to the intermittent reception state based on the DRX transition instruction information.

  When the downlink control information indicates a transition to intermittent reception (ST102-Yes), the user terminal transitions to an intermittent reception state (ST103). For example, when transition to the intermittent reception state is instructed by the DRX transition instruction information, the user terminal transitions to the intermittent reception state after transmitting UL data (PUSCH signal). At this time, as shown in FIG. 5 above, the user terminal may transition to the intermittent reception state after a predetermined period of time after being instructed to transition to intermittent reception.

  Alternatively, the user terminal may operate so as not to start or restart the drx-InactivityTimer when the transition to the intermittent reception is instructed by the downlink control information (ST102-Yes).

  In addition, when the user terminal receives an instruction to start or restart drx-InactivityTimer after receiving the DRX transition instruction in ST102 and before transitioning to the intermittent reception state, the user terminal performs the transition operation to the intermittent reception state. You may cancel. In addition, even when the user terminal is instructed to transition to the intermittent reception state in ST102, the user terminal cannot receive the delivery confirmation signal (ACK) for the UL data signal (PUSCH signal) transmitted based on the UL grant. May cancel the transition to the intermittent reception state.

  When the downlink control information does not instruct the transition to the intermittent reception state (ST102-No), the user terminal starts or restarts the drx-InactivityTimer (ST104). For example, the radio base station instructs the user terminal not to make a transition to the discontinuous reception (DRX) state in the downlink control information when further transmitting / receiving data.

  In this way, by using the downlink control information (DCI) to instruct the user terminal to make a transition instruction to UL grant and intermittent reception at the same timing, it is possible to save battery in the user terminal while suppressing waste of radio resources. It becomes.

(Second aspect)
In the second aspect, a case will be described in which a MAC terminal (MAC CE) is used to instruct the user terminal to make a transition to the UL grant and the intermittent reception state at the same timing.

  In the second aspect, the radio base station transmits a predetermined MAC CE (for example, DRX command with UL grant MAC CE) instructing UL grant and DRX transition to the user terminal. The user terminal that has received the predetermined MAC CE performs a UL transmission operation and a transition operation to the DRX state (see FIG. 4).

  When the user terminal detects a predetermined MAC CE instructing UL grant and DRX transition, the user terminal does not immediately transition to the intermittent reception state, but controls to transition to the intermittent reception state after a predetermined period after detection. May be. The predetermined period may be set shorter than the period of drx-InactivityTimer. Thereby, communication can be appropriately performed when there is data transmission / reception within a predetermined period from reception of a predetermined MAC CE instructing UL grant and DRX transition. Moreover, it becomes possible to flexibly control the timing at which the user terminal transitions to the intermittent reception state.

  In the present embodiment, the user terminal receives drG-InactivityTimer after receiving a predetermined MAC CE instructing UL grant and DRX transition and before transitioning to intermittent reception (for example, within a predetermined period in FIG. 5). When an instruction for starting or restarting is received separately, the transition operation to intermittent reception by the DRX transition instruction may be stopped (see FIG. 6).

  Further, even when the user terminal receives a predetermined MAC CE instructing UL grant and DRX transition, the user terminal receives an acknowledgment signal (ACK) for the UL data signal (PUSCH signal) transmitted based on the UL grant. If this is not possible, the transition to intermittent reception may be stopped. That is, when the user terminal cannot receive an ACK for the PUSCH, the user terminal may operate so as not to make a transition to DRX in anticipation of a retransmission PDCCH from the radio base station. In this manner, data transmission / reception can be appropriately performed by controlling the transition operation to intermittent reception in consideration of the positive delivery confirmation signal for the PUSCH signal.

  Note that whether or not to apply the DRX transition cancellation operation in the user terminal may be controlled using an RRC signal or a MAC signal from the radio base station. Thereby, it becomes possible to perform DRX control in a user terminal more flexibly according to a communication condition.

  A new MAC CE format can be used as the predetermined MAC CE instructing UL grant and DRX transition. For example, as shown in FIG. 8A, a new MAC CE format (3 bytes) including a UL grant can be used.

  Alternatively, an existing MAC PDU (Protocol Data Unit) format may be used (reused) as a MAC CE instructing UL grant and DRX transition. For example, it is possible to use a random access response (RAR) that can indicate the UL grant in the MAC payload (see FIG. 8B). In this case, when a user terminal receives an RAR for a C-RNTI (Cell Radio Network Temporary Identifier) of the user terminal, the user terminal replaces the RAR with a MAC CE instructing a DRX transition and an UL grant. A reception operation and a DRX transition operation can be performed.

  In the existing RAR, the user terminal can only transmit using RA-RNTI (Random Access RNTI). Therefore, as described above, when using MAC RAR as the MAC CE instructing UL grant and DRX transition, control is performed so that the user terminal operates with expectation of RAR for C-RNTI.

  In this way, by instructing the user terminal to make a transition instruction to UL grant and intermittent reception using the predetermined MAC CE at the same timing, it is possible to save battery in the user terminal while suppressing waste of radio resources. .

(Wireless communication system)
Hereinafter, the radio communication system according to the present embodiment will be described in detail. In this radio communication system, the radio communication method according to the first aspect and the second aspect is applied. In addition, the radio | wireless communication method which concerns on the said 1st aspect and a 2nd aspect may be applied independently, and may be applied in combination as appropriate.

  FIG. 9 is a schematic configuration diagram of the radio communication system according to the present embodiment. As shown in FIG. 9, the radio communication system 1 includes a radio base station 10 that forms a cell C, a user terminal 20, and a core network 30 to which the radio base station 10 is connected. Note that the numbers of the radio base stations 10 and the user terminals 20 are not limited to those shown in FIG.

  Further, the radio base station 10 and the user terminal 20 have hardware including a communication interface, a processor, a memory, a display, and an input key, and a software module executed by the processor is stored in the memory. The functional configurations of the radio base station 10 and the user terminal 20 may be realized by the above-described hardware, may be realized by a software module executed by a processor, or may be realized by a combination of both. Good.

  The radio base station 10 is a radio base station having a predetermined coverage. The radio base station 10 may be a macro base station (eNodeB, macro base station, aggregation node, transmission point, transmission / reception point) having a relatively wide coverage, or a small base station having local coverage. (Small base station, pico base station, femto base station, HeNB (Home eNodeB), RRH (Remote Radio Head), micro base station, transmission point, transmission / reception point).

  The radio base station 10 is connected to the core network 30. The core network 30 is provided with core network devices such as MME (Mobility Management Entity), S-GW (Serving-Gateway), and P-GW (Packet-Gateway). The MME provided in the core network 30 is a device that performs mobility management of the user terminal 20, and may be connected to the radio base station 10 through a C-plane interface (for example, an S1-C interface).

  The S-GW provided in the core network 30 is a device that processes user data transmitted from the radio base station 10 to the user terminal 20, and is a radio base station using a U-plane interface (for example, an S1-U interface). 10 may be connected.

  The user terminal 20 is a terminal that supports various communication schemes such as LTE, LTE-A, and FRA, and may include not only a mobile communication terminal but also a fixed communication terminal. The user terminal 20 performs downlink / uplink communication with the radio base station 10.

  Here, communication channels used in the wireless communication system shown in FIG. 9 will be described. The downlink communication channel includes a PDSCH (Physical Downlink Shared Channel) shared by each user terminal 20 and a downlink L1 / L2 control channel (PDCCH, PCFICH, PHICH, extended PDCCH). User data and higher control information are transmitted by the PDSCH. PDSCH and PUSCH scheduling information and the like are transmitted by PDCCH (Physical Downlink Control Channel). The number of OFDM symbols used for PDCCH is transmitted by PCFICH (Physical Control Format Indicator Channel). HARQ ACK / NACK for PUSCH is transmitted by PHICH (Physical Hybrid-ARQ Indicator Channel). Moreover, scheduling information of PDSCH and PUSCH may be transmitted by the extended PDCCH (EPDCCH). This EPDCCH is frequency division multiplexed with PDSCH (downlink shared data channel).

  The uplink communication channel includes a PUSCH (Physical Uplink Shared Channel) as an uplink data channel shared by each user terminal 20 and a PUCCH (Physical Uplink Control Channel) that is an uplink control channel. User data and higher control information are transmitted by this PUSCH. Further, downlink channel state information (CSI), ACK / NACK, and the like are transmitted by PUCCH.

  In the wireless communication system 1, a frequency division duplex (FDD) scheme may be used as a duplex scheme, or a time division duplex (TDD) scheme may be used. However, both may be used.

  FIG. 10 is an overall configuration diagram of the radio base station 10 according to the present embodiment. The radio base station 10 includes a plurality of transmission / reception antennas 101 for MIMO transmission, an amplifier unit 102, a transmission / reception unit (transmission unit / reception unit) 103, a baseband signal processing unit 104, a call processing unit 105, a transmission And a road interface 106.

  User data transmitted from the radio base station 10 to the user terminal 20 via the downlink is input to the baseband signal processing unit 104 via the transmission path interface 106.

  The baseband signal processing unit 104 performs PDCP layer processing, user data division / combination, RLC layer transmission processing such as RLC (Radio Link Control) retransmission control transmission processing, MAC (Medium Access Control) retransmission control, for example, HARQ transmission processing, scheduling, transmission format selection, channel coding, inverse fast Fourier transform (IFFT) processing, and precoding processing are performed and transferred to each transceiver 103. The downlink control channel signal is also subjected to transmission processing such as channel coding and inverse fast Fourier transform, and is transferred to each transceiver 103.

  In addition, the baseband signal processing unit 104 notifies information (DRX transition instruction information) for the user terminal 20 to control the intermittent reception operation (transition operation to intermittent reception). The DRX transition instruction information can be notified to the user terminal using downlink control information (for example, DCI including UL grant) or a predetermined MAC CE (MAC CE instructing DRX).

  Each transmission / reception unit 103 converts the baseband signal output by precoding for each antenna from the baseband signal processing unit 104 to a radio frequency band. The amplifier unit 102 amplifies the frequency-converted radio frequency signal and transmits the amplified signal using the transmission / reception antenna 101. The transmission / reception unit 103 functions as a transmission unit that transmits a DL signal including at least UL grant and DRX transition instruction information.

  On the other hand, for data transmitted from the user terminal 20 to the radio base station 10 via the uplink, radio frequency signals received by the respective transmission / reception antennas 101 are amplified by the amplifier units 102 and frequency-converted by the respective transmission / reception units 103. It is converted into a baseband signal and input to the baseband signal processing unit 104.

  The baseband signal processing unit 104 performs FFT processing, IDFT processing, error correction decoding, MAC retransmission control reception processing, RLC layer, and PDCP layer reception processing on user data included in the input baseband signal. And transferred to the core network 30 via the transmission path interface 106. The call processing unit 105 performs call processing such as communication channel setting and release, status management of the radio base station 10, and radio resource management.

  FIG. 11 is a main functional configuration diagram of baseband signal processing section 104 included in radio base station 10 according to the present embodiment. As shown in FIG. 11, the baseband signal processing unit 104 included in the radio base station 10 includes a control unit 301, a DL signal generation unit 302, a mapping unit 303, a UL signal demodulation unit 304, a determination unit 305, Is included.

  The control unit 301 controls scheduling (DL allocation control) of downlink user data transmitted on the PDSCH, downlink control information transmitted on the PDCCH and / or enhanced PDCCH (EPDCCH), downlink reference signals, and the like. In addition, the control unit 301 also performs uplink data transmission on the PUSCH, uplink control information transmitted on the PUCCH or PUSCH, and uplink reference signal scheduling control (UL allocation control). Information related to allocation control of uplink signals (uplink control signals, uplink user data) is notified to user terminals using downlink control signals (DCI).

  Specifically, the control unit 301 controls allocation of radio resources for downlink signals and uplink signals based on instruction information from the core network 30 and feedback information from each user terminal 20. That is, the control unit 301 has a function as a scheduler. Moreover, the control part 301 can also control intermittent reception (DRX) operation | movement in a user terminal.

  For example, when the control unit 301 causes the user terminal to transition to the intermittent reception state together with the UL assignment, the DL signal generation unit 302 generates UL grant and information on the transition instruction to the intermittent reception state (DRX transition instruction information). To instruct.

  The DL signal generation unit 302 generates a MAC control element (MAC CE) and a physical downlink channel signal. For example, the DL signal generation unit 302 generates a downlink control signal (PDCCH signal and / or EPDCCH signal) and a downlink data signal (PDSCH signal) whose assignment has been determined by the control unit 301. Specifically, the DL signal generation unit 302, based on an instruction from the control unit 301, a DL allocation (DL assignment) for notifying downlink signal allocation information and a UL grant (DL grant) for notifying uplink signal allocation information ( UL grant).

  In addition, the DL signal generation unit 302 generates a PDCCH signal including information (DRX transition instruction information) regarding a UL grant and a transition instruction to the intermittent reception state, or a predetermined MAC CE (for example, DRX command with UL grant MAC CE). To do. When generating a predetermined MAC CE, the MAC CE format shown in FIG. 8 can be used.

  The mapping unit 303 controls allocation of the downlink control signal and downlink data signal generated by the DL signal generation unit 302 to radio resources based on an instruction from the control unit 301.

  The UL signal demodulator 304 demodulates a feedback signal (such as a delivery confirmation signal) transmitted from the user terminal using the uplink control channel (PUCCH), and outputs the demodulated signal to the controller 301. UL signal demodulation section 304 demodulates the uplink data signal transmitted from the user terminal through the uplink shared channel (PUSCH), and outputs the demodulated data signal to determination section 305.

  The determination unit 305 performs retransmission control determination (ACK / NACK) based on the demodulation result of the UL signal demodulation unit 304 and outputs the result to the control unit 301. Note that the result (delivery confirmation signal) determined by the determination unit 305 is notified to the user terminal using PHICH (Physical Hybrid-ARQ Indicator Channel).

  FIG. 12 is an overall configuration diagram of the user terminal 20 according to the present embodiment. The user terminal 20 includes a plurality of transmission / reception antennas 201 for MIMO transmission, an amplifier unit 202, a transmission / reception unit (transmission unit / reception unit) 203, a baseband signal processing unit 204, and an application unit 205. .

  For downlink data, radio frequency signals received by a plurality of transmission / reception antennas 201 are respectively amplified by an amplifier unit 202, frequency-converted by a transmission / reception unit 203, and converted into a baseband signal. The baseband signal is subjected to FFT processing, error correction decoding, retransmission control reception processing, and the like by the baseband signal processing unit 204. Among the downlink data, downlink user data is transferred to the application unit 205. The application unit 205 performs processing related to layers higher than the physical layer and the MAC layer. Also, broadcast information in the downlink data is also transferred to the application unit 205. The transmission / reception unit 203 functions as a reception unit that receives a DL signal including UL grant and DRX transition instruction information.

  On the other hand, uplink user data is input from the application unit 205 to the baseband signal processing unit 204. The baseband signal processing unit 204 performs retransmission control (H-ARQ (Hybrid ARQ)) transmission processing, channel coding, precoding, DFT processing, IFFT processing, and the like, and forwards them to each transmission / reception unit 203. The transmission / reception unit 203 converts the baseband signal output from the baseband signal processing unit 204 into a radio frequency band. Thereafter, the amplifier unit 202 amplifies the frequency-converted radio frequency signal and transmits the amplified signal using the transmission / reception antenna 201.

  FIG. 13 is a main functional configuration diagram of the baseband signal processing unit 204 (which may include the application unit 205) included in the user terminal 20. As shown in FIG. 13, the baseband signal processing unit 204 included in the user terminal 20 includes a DL signal demodulation unit 401, a DRX control unit 402 (timer management unit 402a, DRX state management unit 402b), and a control unit (feedback control). Part) 403, UL signal generation section 404, and mapping section 405.

  The DL signal demodulator 401 demodulates the downlink control signal (PDCCH signal) transmitted on the downlink control channel (PDCCH) and outputs scheduling information (uplink resource allocation information) to the DRX controller 402 and the controller 403. . The DL signal demodulator 401 demodulates a downlink data signal transmitted on the downlink shared channel (PDSCH).

  The DRX control unit 402 includes a timer management unit 402a and a DRX state management unit 402b, and controls discontinuous reception (DRX) operation in the user terminal. The timer management unit 402a manages a predetermined timer (for example, drx-InactivityTimer) related to the DRX operation. For example, when the drx-InactivityTimer expires, the timer management unit 402a notifies the DRX state management unit 402b. The DRX state management unit 402b manages the DRX state (such as transition to the DRX state) in the user terminal.

  For example, when receiving a DL signal including a UL grant, the DRX control unit 402 controls the application of intermittent reception based on DRX transition instruction information included in the DL signal. When the transition to the intermittent reception state is instructed by the DL signal including the UL grant, the DRX control unit 402 can control to transition to the intermittent reception state after a predetermined period (see FIG. 5 above).

  Also, the DRX control unit 402 receives an instruction to start or restart the drx-InactivityTimer after the transition to the intermittent reception state is instructed by the DL signal including the UL grant and before the transition to the intermittent reception state. In this case, the transition to the intermittent reception state may be stopped (see FIG. 6 above).

  Also, the DRX control unit 402 is in the intermittent reception state when it cannot receive the ACK for the UL signal transmitted based on the UL grant even when the transition to the intermittent reception state is instructed by the DL signal including the UL grant. You may cancel the transition to.

  The control unit 403 controls the generation of the uplink control signal (feedback signal) and the uplink data signal based on the downlink control signal (PDCCH signal) transmitted from the radio base station and the retransmission control determination result for the received PDSCH signal. . The control unit 403 also functions as a feedback control unit that controls the feedback of the delivery confirmation signal (A / N) with respect to the PDSCH signal. When it is determined that the transition from the DRX control unit 402 to the intermittent reception state is made, the control unit 403 stops the operation.

  The UL signal generation unit 404 generates an uplink control signal (feedback signal such as a delivery confirmation signal or channel state information (CSI)) based on an instruction from the control unit 403. Further, the UL signal generation unit 404 generates an uplink data signal based on an instruction from the control unit 403.

  Based on an instruction from the control unit 403, the mapping unit 405 (allocation unit) controls the allocation of uplink control signals (such as acknowledgment signals) and uplink data signals to radio resources (PUCCH, PUSCH).

  Although the present invention has been described in detail using the above-described embodiments, it is obvious to those skilled in the art that the present invention is not limited to the embodiments described in this specification. The present invention can be implemented as modified and changed modes without departing from the spirit and scope of the present invention defined by the description of the scope of claims. For example, the above-described plurality of aspects can be applied in appropriate combination. Therefore, the description of the present specification is for illustrative purposes and does not have any limiting meaning to the present invention.

  This application is based on Japanese Patent Application No. 2014-101526 of May 15, 2014 application. All this content is included here.

Claims (5)

A receiver for receiving a DL signal including at least a UL grant;
A DRX control unit for controlling the intermittent reception operation,
The DRX control unit, the user terminal when receiving a DL signal, and controls the intermittent receiving operation based on the information that is part of to the DL signal containing the UL grant. The DRX control unit, said even if the transition based on the information contained in the DL signal including the UL grant to the intermittent reception state is instructed, the drx-InactivityTimer before entering the discontinuous reception mode started or The user terminal according to claim 1, wherein the active state is continued when a restart instruction is received. Information included in the DL signal, the user terminal according to claim 1 or claim 2, characterized in that it is transmitted by being down control channel included in the downlink control information for instructing the UL transmission. A transmitter that transmits a UL grant instructing the user terminal to assign a UL;
Anda generating unit for generating instructions information for controlling the intermittent receiving operation of the user terminal,
And the transmission unit, a radio base station and transmits the instruction information at the same timing as UL grant. A wireless communication method of a user terminal end that performs intermittent reception,
Comprising: receiving a DL signal including at least UL Grants,
The UL when receiving a DL signal including Grants, wireless communication method characterized by having a step of controlling the intermittent receiving operation based on the information contained in the DL signal.

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